Method of manufacturing casing of turbocharger and casing of turbocharger

Abstract

A method of manufacturing a casing of a turbocharger includes: a steam treatment step of subjecting at least one of a turbine housing and a bearing housing to a steam treatment to form an oxide film on the at least one of the turbine housing and the bearing housing before assembling the turbine housing, the bearing housing and a compressor housing; and an assembling step of assembling the turbine housing, the bearing housing and the compressor housing.

The invention claimed is: 
     
       1. A method of manufacturing a casing of a turbocharger,
 the casing including a turbine housing that houses a turbine rotor of the turbocharger, a bearing housing that houses a bearing that rotatably supports the turbine rotor, and a compressor housing that houses a compressor impeller of the turbocharger, the method comprising: 
 a steam treatment step of subjecting at least one of the turbine housing and the bearing housing to a steam treatment to form an oxide film on the at least one of the turbine housing and the bearing housing; and 
 an assembling step of assembling the turbine housing, the bearing housing and the compressor housing, 
 wherein the steam treatment step includes: 
 a turbine housing steam treatment step of subjecting the turbine housing to the steam treatment to form an oxide film on the turbine housing before assembling the turbine housing, the bearing housing and the compressor housing; and 
 a bearing housing steam treatment step of subjecting the bearing housing to the steam treatment to form an oxide film on the bearing housing before assembling the turbine housing, the bearing housing and the compressor housing, 
 wherein the method further comprising: 
 a turbine housing machining step of machining the turbine housing; and 
 a bearing housing machining step of machining the bearing housing, 
 wherein
 the turbine housing machining step is performed between the turbine housing steam treatment step and the assembling step, and 
 
 the bearing housing machining step is performed between the bearing housing steam treatment step and the assembling step, 
 wherein 
 the turbine housing includes a first portion that fits with the bearing housing, 
 the bearing housing includes a second portion that fits with the first portion of the turbine housing, 
 in the turbine housing machining step, an oxide film formed on at least the first portion of the turbine housing is removed by machining after the turbine housing steam treatment step, and 
 in the bearing housing machining step, an oxide film formed on at least the second portion of the bearing housing is removed by machining after the bearing housing steam treatment step. 
 
     
     
       2. The method of manufacturing the casing of the turbocharger according to  claim 1 , wherein
 the compressor housing is not subjected to the steam treatment. 
 
     
     
       3. The method of manufacturing the casing of the turbocharger according to  claim 1 , further comprising:
 a turbine housing molding step of molding the turbine housing while leaving a cutting allowance in at least the first portion of the turbine housing; and 
 a bearing housing molding step of molding the bearing housing while leaving a cutting allowance in at least the second portion of the bearing housing. 
 
     
     
       4. The method of manufacturing the casing of the turbocharger according to  claim 3 , wherein
 in the turbine housing machining step, an oxide film formed on at least the first portion of the turbine housing and the cutting allowance of the turbine housing are removed by machining, and 
 in the bearing housing machining step, an oxide film formed on at least the second portion of the bearing housing and the cutting allowance of the bearing housing are removed by machining. 
 
     
     
       5. The method of manufacturing the casing of the turbocharger according to  claim 1 , wherein
 the turbocharger further includes: 
 a wastegate valve; 
 an actuator that generates driving force for opening and closing the wastegate valve; and 
 a drive transmission mechanism for transmitting the driving force from the actuator to the wastegate valve, and 
 the drive transmission mechanism includes a rod and a pin inserted through a rod hole formed in the rod, the method further including: 
 a step of subjecting at least one of an inner peripheral surface of the rod hole and an outer peripheral surface of the pin to the steam treatment to form an oxide film. 
 
     
     
       6. A method of manufacturing a casing of a turbocharger,
 the casing including a turbine housing that houses a turbine rotor of the turbocharger, a bearing housing that houses a bearing that rotatably supports the turbine rotor, and a compressor housing that houses a compressor impeller of the turbocharger, the method comprising: 
 a steam treatment step of subjecting at least one of the turbine housing and the bearing housing to a steam treatment to form an oxide film on the at least one of the turbine housing and the bearing housing; and 
 an assembling step of assembling the turbine housing, the bearing housing and the compressor housing, 
 wherein the steam treatment step includes: 
 a turbine housing steam treatment step of subjecting the turbine housing to the steam treatment to form an oxide film on the turbine housing before assembling the turbine housing, the bearing housing and the compressor housing; and 
 a bearing housing steam treatment step of subjecting the bearing housing to the steam treatment to form an oxide film on the bearing housing before assembling the turbine housing, the bearing housing and the compressor housing, 
 wherein the method further comprising: 
 a turbine housing machining step of machining the turbine housing; and 
 a bearing housing machining step of machining the bearing housing, 
 wherein
 the turbine housing machining step is performed between the turbine housing steam treatment step and the assembling step, and 
 
 the bearing housing machining step is performed between the bearing housing steam treatment step and the assembling step, 
 wherein 
 the bearing housing includes: 
 a bearing support portion that supports the bearing; 
 a lubricating-oil inlet-side end surface in which an inlet for lubricating oil to be supplied to the bearing is formed; 
 a lubricating-oil outlet-side end surface in which an outlet of the lubricating oil is formed; and 
 a third portion that fits with the compressor housing of the turbocharger, and 
 in the bearing housing machining step, an oxide film formed on at least one of the bearing support portion, the lubricating-oil inlet-side end surface, the lubricating-oil outlet-side end surface, and the third portion is removed by machining after the bearing housing steam treatment step. 
 
     
     
       7. The method of manufacturing the casing of the turbocharger according to  claim 6 , wherein
 the compressor housing is not subjected to the steam treatment. 
 
     
     
       8. The method of manufacturing the casing of the turbocharger according to  claim 6 , wherein
 the turbocharger further includes: 
 a wastegate valve; 
 an actuator that generates driving force for opening and closing the wastegate valve; and 
 a drive transmission mechanism for transmitting the driving force from the actuator to the wastegate valve, and 
 the drive transmission mechanism includes a rod and a pin inserted through a rod hole formed in the rod, the method further including: 
 a step of subjecting at least one of an inner peripheral surface of the rod hole and an outer peripheral surface of the pin to the steam treatment to form an oxide film. 
 
     
     
       9. A method of manufacturing a casing of a turbocharger, the casing including a turbine housing that houses a turbine rotor of the turbocharger, a bearing housing that houses a bearing that rotatably supports the turbine rotor, and a compressor housing that houses a compressor impeller of the turbocharger, the method consisting of:
 a steam treatment step of subjecting at least one of the turbine housing and the bearing housing to a steam treatment to form an oxide film on the at least one of the turbine housing and the bearing housing; 
 a housing machining step of machining at least one of the turbine housing and the bearing housing; and 
 an assembling step of assembling the turbine housing, the bearing housing and the compressor housing, 
 wherein the steam treatment step is consisted of: 
 a turbine housing steam treatment step of subjecting the turbine housing to the steam treatment to form an oxide film on the turbine housing before assembling the turbine housing, the bearing housing and the compressor housing; and 
 a bearing housing steam treatment step of subjecting the bearing housing to the steam treatment to form an oxide film on the bearing housing before assembling the turbine housing, the bearing housing and the compressor housing, 
 wherein the housing machining step is consisted of: 
 a turbine housing machining step of machining the turbine housing; and 
 a bearing housing machining step of machining the bearing housing, wherein 
 the turbine housing steam treatment step is performed between the turbine housing machining step and the assembling step, and 
 the bearing housing steam treatment step is performed between the bearing housing machining step and the assembling step, 
 wherein 
 no machining is performed on the turbine housing after the turbine housing steam treatment step, 
 no machining is performed on the bearing housing after the bearing housing steam treatment step, 
 the turbine housing includes a first portion that fits with the bearing housing, the first portion being a portion whose surface is machined in the turbine housing machining step, 
 the bearing housing includes a second portion that fits with the first portion of the turbine housing, the second portion being a portion whose surface is machined in the bearing housing machining step, 
 in the assembling step, the oxide film formed in the turbine housing steam treatment step exists on a machined surface of the first portion and the oxide film formed in the bearing housing steam treatment step exists on a machined surface of the second portion, and the turbine housing and the bearing housing are assembled so that the first portion of the turbine housing and the second portion of the bearing housing are fitted together, 
 the thickness of the oxide film formed on the turbine housing including the first portion in the turbine housing steam treatment step is 10 to 30 μm, and 
 the thickness of the oxide film formed on the bearing housing including the second tion in the bearing housing steam treatment step is 10 to 30 μm. 
 
     
     
       10. The method of manufacturing the casing of the turbocharger according to  claim 9 , wherein
 the compressor housing is not subjected to the steam treatment. 
 
     
     
       11. The method of manufacturing the casing of the turbocharger according to  claim 9 , wherein
 the turbocharger further includes: 
 a wastegate valve; 
 an actuator that generates driving force for opening and closing the wastegate valve; and 
 a drive transmission mechanism for transmitting the driving force from the actuator to the wastegate valve, and 
 the drive transmission mechanism includes a rod and a pin inserted through a rod hole formed in the rod, the method further consisting of: 
 a step of subjecting at least one of an inner peripheral surface of the rod hole and an outer peripheral surface of the pin to the steam treatment to form an oxide film. 
 
     
     
       12. A method of manufacturing the casing of the turbocharger
 the casing including a turbine housing that houses a turbine rotor of the turbocharger, a bearing housing that houses a bearing that rotatably supports the turbine rotor, and a compressor housing that houses a compressor impeller of the turbocharger, the method comprising: 
 a steam treatment step of subjecting at least one of the turbine housing and the bearing housing to a steam treatment to form an oxide film on the at least one of the turbine housing and the bearing housing; and 
 an assembling step of assembling the turbine housing, the bearing housing and the compressor housing, 
 wherein the steam treatment step includes: 
 a turbine housing steam treatment step of subjecting the turbine housing to the steam treatment to form an oxide film on the turbine housing before assembling the turbine housing, the bearing housing and the compressor housing; and 
 a bearing housing steam treatment step of subjecting the bearing housing to the steam treatment to form an oxide film on the bearing housing before assembling the turbine housing, the bearing housing and the compressor housing, 
 wherein the method further comprises: 
 a turbine housing machining step of machining the turbine housing; and 
 a bearing housing machining step of machining the bearing housing, 
 wherein 
 the turbine housing steam treatment step is performed between the turbine housing machining step and the assembling step, and 
 the bearing housing machining step is performed between the bearing housing steam treatment step and the assembling step, 
 no machining is performed on the turbine housing after the turbine housing steam treatment step, 
 the turbine housing includes a first portion that fits with the bearing housing, 
 the bearing housing includes a second portion that fits with the first portion of the turbine housing, 
 in the assembling step, the turbine housing and the bearing housing are assembled so that the first portion of the turbine housing and the second portion of the bearing housing are fitted together, 
 the thickness of the oxide film formed on the turbine housing in the turbine housing steam treatment step is 10 to 30 μm, and 
 in the bearing housing machining step, an oxide film formed on at least the second portion of the bearing housing is removed by machining after the bearing housing steam treatment step. 
 
     
     
       13. The method of manufacturing the casing of the turbocharger according to  claim 12 , wherein,
 the compressor housing is not subjected to the steam treatment. 
 
     
     
       14. The method of manufacturing the casing of the turbocharger according to  claim 12 , wherein
 the turbocharger further includes: 
 a wastegate valve; 
 an actuator that generates driving force for opening and closing the wastegate valve; and 
 a drive transmission mechanism for transmitting the driving force from the actuator to the wastegate valve, and 
 the drive transmission mechanism includes a rod and a pin inserted through a rod hole formed in the rod, the method further including: 
 a step of subjecting at least one of an inner peripheral surface of the rod hole and an outer peripheral surface of the pin to the steam treatment to form an oxide film.